The subject matter described herein relates generally to the field of electronic communication and more particularly to differential delay compensation.
Communication networks transmit data from an originator to a destination via a communication network that may include multiple transfer points, such as hardware routers, that receive data typically in the form of packets or data frames. Data transmission over fiber optics networks may conform to SONET and/or SDH standards. SONET and SDH are a set of related standards for synchronous data transmission over fiber optic networks. SONET is short for Synchronous Optical NETwork and SDH is an acronym for Synchronous Digital Hierarchy.
SONET/SDH networks may employ virtually concatenated payloads. Virtual concatenation partitions payload data into multiple virtual containers that may be assigned a single index, referred to as a Multiframe Indicator (MFI), and transmitted contemporaneously across different transmission media and/or different network paths. Because the payload data traverses different network paths, payload data transmitted contemporaneously can be received at different times, an effect referred to as differential delay. Differential delay can also result from pointer processing, or from other considerations.
Virtual concatenation compensates for differential delay at the receiving entity by reassembling the payload in an appropriate time-ordered sequence. Data from different members of a virtual concatenation group are stored in a memory at the receiver. Processing logic in the destination node reads payload data from members having the same MFI contemporaneously. To do this, the destination node may determine memory locations of members in the same group having the same MFI value at the same byte within the frame so that the data can be assembled correctly at the output of the data memory. Addressing data in this arrangement can be complex, as data is being received, assembled, and processed at varying points and may require data reading from or writing to the memory based on a variety of circumstances.